A 1.5 tonne building block has already been produced for demonstration purposes

The European Space Agency (ESA) is looking to build a lunar base with 3D printing using local materials on the moon.

The idea behind this project is to offer settlement for astronauts on the moon while using less of Earth's resources to do so.

ESA has partnered with architectural firms like Foster + Partners to see whether lunar soil could be used for a 3D printed lunar base. In fact, Foster + Partners has already designed a "catenary" dome, which is a hollow closed-cell structure complete with a wall that protects against space radiation and micrometeoroids.

A 1.5 tonne building block has already been produced for demonstration purposes, as seen below:

The 3D structures are built layer-by-layer. The lunar material would be combined with magnesium oxide, which turns it into a "paper" to be printed with. Then, for the "ink," a binding salt is added to transform the material into a solid. The architects are trying to create a structure that can handle the harsh weather and environment that the moon can have.

“3D printing offers a potential means of facilitating lunar settlement with reduced logistics from Earth,” said Scott Hovland of ESA’s human spaceflight team.
“The new possibilities this work opens up can then be considered by international space agencies as part of the current development of a common exploration strategy.”

Whatever the shelter is made of, it needs to be like armor. That means it's going to be heavy as hell and thick. There is no atmosphere to protect them from meteors.They just need to replay some episodes of "Space 1999" and see how they did it....lol. I miss that show.

It does not have to be heavy in the lighter gravity it would be possible to make glass "foam" which could be molded into any shape easiest would be half moon shape add an air tight liner on the inside bury it and done.

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